(a) Field of the Invention
The present invention relates to a device for varying a stroke of a clutch pedal. More particularly, the present invention relates to a device for varying a stroke of a clutch pedal applied to a pedal unit of a clutch system of a manual transmission and varying an effective stroke of a clutch pedal depending on a vehicle speed signal and an engine RPM signal thereby preventing energy collision noise of a driving system.
(b) Description of the Related Art
Generally, a clutch system of a vehicle plays a role of selectively delivering power of an engine to a drive wheel, and temporarily cuts off power of an engine during an engine starting or a gear shifting of a transmission.
Such a clutch system can be divided into a mechanical type using a rod or a wire and a hydraulic pressure type using hydraulic pressure depending on an operating power transmission method.
FIG. 5 shows an example of a clutch system of a hydraulic pressure type, a clutch master cylinder 103 operated by a clutch pedal 101 is connected to a clutch release cylinder 107 via a hose 105, and a pushrod 109 of the clutch release cylinder 107 is connected to a release fork 111.
That is, an operation process originated from the clutch pedal 101 acts on a clutch disk 115 via the clutch master cylinder 103, the hose 105, the clutch release cylinder 107, the clutch fork 111, and the clutch release bearing 113, thereby cutting off power transmission.
In such a conventional clutch system, shock noise is generated in a driving system when acceleration is performed by shifting gears just after an engine starting or when acceleration is performed under great torque by shifting gears while a vehicle runs. Such noise is caused by an energy collision generated by a collision of engine rotation energy and vehicle weight energy (i.e., weight of a vehicle and driving inertia energy of a vehicle). Such noise is amplified by a transmission, a propeller shaft, a rear axle, and the like, and is then transmitted to a vehicle body.
If a driver depresses the clutch pedal 101 with a full stroke, which means a stroke including an effective stroke of a clutch pedal of about 30 to 35 mm allowing an engagement of a clutch gear, the clutch disk 115 is completely separated from a friction plate 119 of a flywheel 117. In such a state, if the clutch pedal 101 is released, the clutch disk 115 in a stopped state contacts the rotating friction plate 119 of the flywheel 117 in an axial direction by a diaphragm spring 123 on a clutch cover 121, and this causes an energy collision generated in the clutch system.
That is, as a gap between the flywheel 117 and the clutch disk 115 becomes greater, a speed of the clutch disk 115 at the moment of contacting the friction plate 119 of the flywheel 117 becomes faster, and contact shock in an axial direction becomes also greater. Therefore, the contact shock between the clutch disk 115 and the friction plate 119 of the flywheel 117 in an axial direction is amplified by rotation energy of a driving system, thereby generating energy collision noise.
In the case in which a difference between rotation energy of an engine and weight energy of a vehicle is relatively great such as the case acceleration is performed just after engine starting or acceleration is performed under great torque by gear shifting wile a vehicle runs, if a gap between the clutch disk 15 and the friction plate 119 of the flywheel 117 is minutely regulated by minimizing an effective stroke of the clutch pedal 101 for an engagement of a clutch gear, a contact speed of the clutch disk 115 and the flywheel 117 can be minimized, and thereby contact shock in axial direction can be minimized so that noise caused by energy collision in the driving system can be reduced.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.